In the serial production of sand-mold parts it is standard to use a so-called caseless mold which has a normally stationary box with a pair of opposite open ends each of which can be closed by a respective mold plate. When closed the interior surfaces of the box and the confronting faces of the mold plates define a mold cavity which is filled with mold sand, also termed grog, ganister, or chamotte, that is then compressed to take on a shape corresponding to the mold cavity. After compression one of the mold plates is retracted and moved to the side and the mold part is pushed out of the mold by the other mold plate and is separated from this other plate. In some systems a series of such mold parts is then pressed longitudinally together to form a succession of pockets which are filled with molten metal to make the desired articles, for instance wheels.
In order to reduce wear to the interior faces of the mold box and the faces of the mold plates and to facilitate separation of the molded body, it is standard practice to spray them with a liquid, normally mainly oil. This step is essential to limit wear and to make the molded body separate cleanly from the mold faces.
The standard procedure to thus coat the mold faces is simply to spray them with the mold-release/lubricating liquid when the mold is open. This is, obviously, a very messy operation. The oily liquid runs all over the machine, creating a wet mess where grit can lodge and find a home. In addition some of the liquid inherently becomes airborne so that it travels somewhat from the machine to deposit on adjacent structure and be breathed by the workers manning the equipment.
An attempt has been made to limit the dispersion of the coating liquid by spraying it into the mold cavity when it is at least partially closed. It has also been suggested to use an airless liquid-injection system to spray the interior faces of the mold. Such procedures have been found to provide very poor coating action unless a great deal of the liquid is used. This not only wastes the liquid, but can soak the sand being used for the mold part, making it impossible to reuse.